1. Field
The disclosure relates to a method, system, and article of manufacture for the writing of new data of a first block size in a Redundant Array of Independent Disks (RAID) array that stores both parity and data in a second block size.
2. Background
Redundant Array of Independent Disks (RAID) is a category of disk drives that combine two or more disk drives to provide fault tolerance for data. RAID allows for the redundant storage of the same data across a plurality of disks. In certain configurations of RAID, such as RAID-5 or RAID-6, parity information may also be stored to recover from a failure of one or more disks. The physical disks of a RAID may be said to be in a RAID array that may be addressed by an operating system as one single disk. Data may be written in stripes in a RAID array, wherein data striping is the spreading out of blocks of each file across a plurality of disk drives.
A sector is a specifically sized division of a disk. Previously, one sector of a disk was generally configured to hold 512 bytes of information. However, recently certain disks are being configured to hold 4096 bytes (i.e., 4 Kilobyte) of information by disk manufacturers.
A block is a group of sectors of a disk that an operating system can address. Count-key-data (CKD) is a disk data organization model of certain operating systems in which the disk is assumed to be comprised of a fixed number of tracks, each having a maximum data capacity. Multiple records of varying length may be written on each track of a CKD disk, and the usable capacity of each track depends on the number of records written to the track. CKD architecture derives its name from the record format, which comprises a field containing the number of bytes of data and a record address, an optional key field, and the data itself. CKD records are stored in 512 byte blocks.